Reply by MisterBill

Below is some information from the label on my can of Minwax Wood Hardener that might be useful:

Minwax High Performance Wood Hardener is a quick-drying liquid, formulated to strengthen and reinforce decayed or rotten wood. The hardener penetrates deep into the wood and its special resin binds and reinforces the decayed wood fibers. The wood is sealed against further moisture penetration and hardens to a rock-solid base for filling.

At first I had the same thought as Nomad that Wood Hardener might be a solution. However after reading the label I have my doubts. I suggest using the tried and true method of trying it on a piece of scrap and go from there.